Cook, who has lasted a total of 9 2/3 innings in his last three starts, all losses, is expected to be placed on the 15-day disabled list. The move would facilitate Jhoulys Chacin, currently at Triple A Colorado Springs, moving into the rotation.

Chacin could take Cook’s place on the mound on Sunday, when the Rockies wrap up a four-game series at Pittsburgh.

Cook had been 3-0, 3.25 at Coors Field, which kept him in the rotation despite a 1-6, 6.17 record on the road. But after he lost both of his starts on the Rockies’ homestand, he was summoned to a closed-door meeting with manager Jim Tracy, pitching coach Bob Apodaca and others.

Chacin has had the exact opposite season as Cook. He has struggled at home and pitched brilliantly at times on the road. He’s 3-3, 5.58 at Coors Field, but has fallen victim to a lack of support on the road, where he’s 2-5 despite a 2.57 ERA.